Comment by potatolicious

> "on what timescale though?"

Depends on how extensive the growth is and how structurally stable the thing is in the first place. But expect major problems on the decades-timescale.

> "and in an invisible way?"

Yes. This is the main problem with allowing unconstrained plant growth near/in/under structures - the degree of structural compromise is hard to assess (especially without spending a lot of $$$), and failure can be sudden. You're not gonna get as much warning as you'd want.

In the US it's a popular look to have vines growing against brick walls. They're beautiful but often hazardous for structural safety, especially if not proactively maintained and constantly monitored (which is $$$!)

[edit] I think overall the focus on the "pleasantly ramshackle" aesthetics of the shack misses the forest for the trees. There's a lot of daylight between "permit small businesses in possibly unsafe structures" and "western status quo norms for business licensure".

I think something Japan gets done really well is making it easy and inexpensive to run businesses, especially hobby businesses. There are a ton of policies that encourage this outcome, and we can and should adopt entire rafts of them without changing existing regs about the physical structural stability of said businesses ;)